The National Tranportation Safety Board, citing a rough stone walls on the George Washington Memorial Parkway as a "hazardous" example, recommended yesterday that the National park Service develop and install attractive, safe roadside barriers to replace ones that are attractive but unsafe.

The agency, in a safety recommendation to the Secretary of Interior, asked that the Park Service request the assistance of the Federal Highway Administration in "developing attractive . . .traffic barriers that minimize hazards."

The safety board called for a program to "improve existing and future barriers under jurisdiction of the National Park Service" upon completion of the research.

Henry Wakeland, director of the board's bureau of plans and programs, said, "basically, the Park Service doesn't follow the federal highway standards nationally. They have all sorts of barriers."

Yesterday's formal recommendation said that in 1971 the board had advised construction of better barriers on parkway bridges in Virginia and that this had been done with good safety results.

However, the park Service recently repaired a wall on the George Washington Parkway about a half mile north of Key Bridge with the same rough, irregular stone used in its original construction. That stone contains "snags . . .as much as six inches deep and . . .would contact the side or bumpers of any car which moves five feet beyond the normal path," the board said.

The rough surface can increase the severity of impact by snagging a vehicle and causing it to spin and can make it likely that a large vehicle such as a bus could override the barrier, the board said.

"There was no apparent effort made to update the barrier to improve its safety performance," the board said.

The board said it understood the park Service's desire maintain the attractive environment of the parkway and the view that the parkway was not intended to be a major highway.

The NTSB said, however, that the parkway is a major commuter highway and the primary bus route to Dulles International Airport, and "a safe barrier design does not necessarily require an unattractive appearance."

A spokesman for the Park Service said, "We would agree that attractiveness and safety should go hand in hand. We were not aware that this was a problem and we were not aware that a study was being done on this. We're somewhat puzzled that they didn't bring it to our attention."